JPH04278362A - Piezoelectric print head - Google Patents

Abstract

PURPOSE:To obtain a high-reliability piezoelectric printing head free from the occurrence of a tensile stress in a piezoelectric element relating to a piezoelectric printing head which can perform printing at a high speed by using a piezoelectric element as an actuator. CONSTITUTION:In a piezoelectric printing head which is so constructed that the longitudinal displacement of a piezoelectric element 1 in an electrically conducted state is enlarged by a lever mechanism 5 for conducting printing and is provided with a plurality of parallel springs 31, 32 for pressurizing the piezoelectric element 1 at right angles to the longitudinal direction of the piezoelectric element 1, said springs 31, 32 are disposed on the side opposite to the lever mechanism 5 across the piezoelectric element 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric print head capable of high-speed printing using piezoelectric elements as actuators.

0002

2. Description of the Related Art FIG. 2 is a side view showing the structure of a conventional piezoelectric print head. In the figure, 1 is a piezoelectric element and 2 is a printing wire. The piezoelectric element 1 is formed by laminating a plurality of piezoelectric ceramics through internal electrodes, and each internal electrode is alternately connected to a pair of external electrodes. 31 and 32 are lead wires connected to each external electrode. Base 1 of piezoelectric element 1
a is fixed to the lower part of the frame 4, and the displacement of the piezoelectric element 1 in the longitudinal direction (vertical direction in FIG. 3) when the piezoelectric element 1 is energized is magnified by the lever mechanism 5.

The lever mechanism 5 includes two parallel leaf springs 6,
7 and a beam 9 whose base is connected to a connecting member 8, and the wire 2 is fixed to the tip of the beam 9. The leaf spring 6 has its base connected to the tip 1b of the piezoelectric element, and its tip connected to the connecting member 8, and the leaf spring 7 has its base connected to the upper part of the frame 4, and its tip connected to the connecting member 8, respectively. ing. In this way, by interposing the lever mechanism 5 between the piezoelectric element 1 and the wire 2, the amount of movement of the wire 2 when the piezoelectric element 1 is actuated can be greatly expanded.

By the way, the piezoelectric element 1 has a weakness in that it is extremely weak against tensile stress, and therefore springs 10 and 11 are provided to apply compressive stress to the element in advance. These springs 10 and 11 are arranged perpendicularly to the longitudinal direction of the piezoelectric element 1, and are bent in advance so that the tip end of the piezoelectric element 1
b and frame 4 are connected. As a result, compressive stress is applied to the piezoelectric element 1.

[0005]

[Problems to be Solved by the Invention] However, when a single spring is used for element preload, the spring does not deflect in parallel. Further, even if parallel springs are used, the parallel springs do not bend strictly in parallel due to deformation at the fixed portion of the spring, and as a result, bending stress is generated in the piezoelectric element.

An object of the present invention is to provide a highly reliable piezoelectric print head in which no tensile stress is generated in the piezoelectric element.

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is configured to perform printing by utilizing the displacement in the longitudinal direction of the piezoelectric element when the piezoelectric element is energized. A piezoelectric print head comprising one or more plate springs for applying a preload to the piezoelectric element perpendicular to the longitudinal direction of the piezoelectric element, characterized in that the springs are arranged so that parallel deflection is achieved. The configuration is as follows.

[0008]

[Operation] Since one or more springs are arranged so as to achieve parallel deflection, it is possible to prevent bending stress from occurring in the piezoelectric element.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 2 is a side view showing the structure of the piezoelectric print head of this example. In the figure, 31 and 32 are parallel springs for applying preload, and 33 is a frame. Note that the same reference numerals are used for members similar to those in the past. The springs 31 and 32 are arranged on the opposite side of the lever mechanism 5 with the piezoelectric element 1 in between. Spring 3
1 and 32 are fixed at one end to the tip portion 1b of the piezoelectric element 1 and at the other end to the spring support portion 34 of the frame 33, respectively.

With this configuration, the springs 31 and 32 are deflected in parallel when the print head is operated. this is,
This is because the deflection directions of the springs 31 and 32 and the leaf springs 6 and 7 are opposite to each other and are different from each other. That is, since the preload applying spring is arranged so as to realize parallel deflection, no tensile stress is generated in the piezoelectric element.

0012

As described above, according to the present invention, a piezoelectric element with high reliability can be obtained without generating tensile stress in the piezoelectric element.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the structure of a piezoelectric print head according to an embodiment of the present invention.

FIG. 2 is a side view showing the structure of a conventional piezoelectric print head.

[Explanation of symbols]

1 Piezoelectric element 33 Frame 5 Lever mechanism 6,7 Leaf spring 31, 32 spring

Claims (1)

[Claims] 1. A lever mechanism is configured to magnify the displacement in the longitudinal direction of the piezoelectric element when the piezoelectric element is energized to print, and a preload is applied to the piezoelectric element perpendicular to the longitudinal direction of the piezoelectric element. A piezoelectric print head comprising one or more springs for tensioning, the springs being arranged in such a way that parallel deflections are achieved.